The present invention relates to a portable torque and impulse transmitting machine, such as a hammer drill, which can be used for the drilling of holes in rock, concrete or analogous materials. More particularly, the invention relates to improvements in portable torque and impulse transmitting machines of the type wherein the tool can receive axially oriented impulses to facilitate its penetration into a rock or the like while the tool rotates or while the transmission of torque from a prime mover to the tool is interrupted.
In presently known machines of the above-outlined type, the gear transmission for imparting torque to the tool is relatively complicated and occupies a great amount of space, thus making the gear transmission very expensive. In an attempt to utilize less space, each of the individual gears of the prior-art transmission systems is arranged in different planes. However, the many different orientations of the gears have the drawback that the machine is difficult to service. For example, in some machines, the gears are located within the handle portion of the housing. If one wishes to service these gears, one would have the additional problem of having to remove the top cover of the housing and the handle. Not the least of the disadvantages present in the prior-art machines is that they are too heavy to be easily managed because of their relatively large size.